1. Field of the Invention
The present invention relates to a stalk switch for operating turn signal lamps or windshield wipers attached to a steering column of an automobile.
2. Description of the Related Art
Typically, a pair of stalk switches is attached to a steering column of an automobile. One stalk switch is generally referred to as a turn signal switch for operating turn signal lamps and/or headlights, and the other stalk switch is used for operating windshield wipers or a washing solution. Of these stalk switches, the turn signal switch rotatably supports a base end of an operating lever on a housing integrally formed with the steering column. By rotating the front end of the operating lever from a neutral position to either one of the right and left positions, a turn signal lamp for the right or left direction turns on and off, and by rotating the operating lever in a direction perpendicular to the turn signal position, headlight beam switching or flashing for passing is performed.
In the related art, it has been proposed a turn signal switch in which an operating member fits to an operating lever to integrate them as one piece, a holder is rotatably connected to the operating member protruding from the operating lever, and a pair of supporting shafts provided on the holder is rotatably supported on the housing (for example, see Patent Document 1). In this case, a rotating axis of the operating lever with respect to the housing and a rotating axis of the operating member with respect to the holder are perpendicular to each other, and a driving member is slidably held at the operating member through a spring, and the front end of the driving member always comes into press contact with a cam formed on the inner surface of the holder. In addition, another driving member is slidably held in the holder through a spring, and the front end of the driving member always comes into press contact with another cam formed on the inner surface of the housing.
In the turn signal switch constructed as above, when the operator (i.e., the driver) rotates the operating lever from a neutral position to either one of the right and left positions, the operating lever, the operating member, and the holder integrally rotate around the supporting axis of the holder as a center, and the driving member held in the holder slides along the cam of the housing. Accordingly, the operating lever is locked in a turn signal position, and thus a turn signal lamp for turning to the right or the left turns on and off. In the meantime, when the operator rotates the operating lever in a direction perpendicular to the above turn signal position, the holder does not rotate, and the operating lever and the operating member rotate with respect to the holder. Accordingly, the headlight beam switching or flashing for passing is performed. At this time, the driving member held in the operating member slides along the cam of the holder, and sufficient restoring force builds up in the operating member. Accordingly, the operating lever and the operating member return to the neutral position by the restoring force.
[Patent Document 1]
Japanese Unexamined Patent Application Publication No. 10-269900 (pages 3 to 5, and FIG. 1)
However, in the above-mentioned conventional stalk switch, it is necessary to combine many components, such as a holder having cams, a plurality of driving members, and springs to form a supporting structure for locking the operating lever at a turn signal position or for rotatably operating the operating lever in a direction perpendicular to the turn signal position. Thus, the conventional stalk switch has a very complicated structure, and it costs a great deal to fabricate it. In particular, in the case of the stalk switch as a turn signal switch, when the steering wheel is rotated in a direction opposite to the desired direction in a state in which the operating lever is rotated in the right or left direction, a cancel mechanism should be added to automatically return the operating lever to its neutral position, which causes a more complicated structure due to the added cancel mechanism.
In addition, in this kind of stalk switch, it is common to mount a pair of stalk switches in a common housing to make a combination switch. However, the arrangement of these stalk switches for turn signals and windshield wipers to the right and left of the steering wheel may be different in each country having local road laws and regulations, and various car makers and models of cars have different maintaining forces for locking the operating lever of the turn signal switch at a turn signal position, and different amounts of stroke from the neutral position of the operating lever. As such, in the aforementioned conventional stalk switch, the sizes and shapes of the components constituting the stalk switch must be changed according to various required purposes, thereby degrading general-purpose applicability.